Hybrid image sensors have a photosensitive layer overlaid on and connected to a readout integrated circuit (ROIC) on a silicon chip. For example, the photosensitive layer may comprise a photosensitive film, such as a film containing quantum dots (known as a quantum film). Such sensors often suffer from lack of charge injection efficiency, resulting in non-linearity, lag and non-uniformity of response to incident light.
A typical structure of a hybrid image sensor comprises a photosensitive layer, top and bottom electrodes, and an ROIC. The photosensitive layer can be designed, for example, as a blanket photo-resistive layer with linear signal output as a function of an applied voltage, or with non-linear response to the applied voltage, similar to a photodiode response. The top electrode on the photosensitive layer is typically common for all pixels of the array and transparent to the incoming light. Each pixel has its own bottom electrode. These electrodes are connected to the front-end circuitry of pixels in the ROIC. Pixels in the photosensitive layer can be separated by pixel isolation, which defines the size and pitch of photosensitive pixels in the array. Alternatively, the photosensitive layer can be designed as a continuous blanket layer of photosensitive material. In this case, pixel pitch is defined by the pitch of the bottom electrodes on the photosensitive layer.